Understanding grass species in the Arctic

October 30, 2018

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Sea lymegrass (Leymus mollis), pictured here in Arviat, Nunavut, is a common sight in coastal communities throughout the Arctic. It plays an important role in coast ecosystems by binding sand, which minimizes erosion.

Grass: depending on the day, you might mow it, seed it, or sod it, but outside of these contexts, you probably don’t spend a whole lot of time thinking about grass. Fortunately, botanists at the Canadian Museum of Nature in Ottawa have got you covered. For decades, scientists on our team have been studying the myriad grass species that grow across the Arctic — with over 11,000 species worldwide they are one of the most diverse plant groups up there — and have made many new discoveries along the way.

Dr. Lynn Gillespie, the head of botany at the museum and an Arctic researcher for over 20 years, “had absolutely no intention of working on grasses” when she started her career. Trained as a tropical botanist, Lynn came to the museum as a postdoc with dreams of working in the Arctic, and was promptly put to work by Dr. Susan Aiken, an Arctic grass specialist, on the complicated bluegrass genus Poa.

Dr. Jeff Saarela, on the other hand, comes by his affinity for grasses honestly, having fallen in love with them ever since a fellowship at the Smithsonian Institution in Washington, DC. Shortly after joining the museum in 2007, Jeff participated in a trip to southern Victoria Island (having been introduced to Arctic research by Lynn), collecting plants on both sides of the Nunavut/Northwest Territories border. Ever since he’s been interested in Arctic plants in general and Arctic grasses in particular.

Our team joins a long line of museum botanists interested in northern grasses, from Oscar Malte in the early 1900s through to Susan Aiken and Dr. Laurie Consaul from the ’80s to the 2000s. In fact, there are many professional agrostologists (grass specialists) across the globe. This devoted fan base is due to the challenges posed by these unassuming plants.

Though they aren’t big and showy, grasses do have flowers. In fact, they have many. Found arranged along the tip of the main stem (the “culm”) of grasses, these groups of flowers (an inflorescence) are an array of multiple tiny-wind pollinated florets — a highly reduced flower and two scale-like bracts. Examining these tiny organs is often the key to differentiating grass species — in short, they are often difficult to identify. This challenge invites scientists looking to test their mettle in the arena of describing botanical biodiversity, and generations of researchers have devoted their careers to under­standing these species and providing the public with the tools needed to identify them.

The two Arctic subspecies of Alaska wildrye (Elymus alaskanus) are differentiated by how hairy the inflorescence. Subspecies alaskanum— pictured here — has no hairs on the inflorescence, while the spikelets of subspecies hyparcticum are densely hairy.

Flowers of the bent-awned alpine sweetgrass (Anthoxanthum monticola subsp. alpinum). Though they are much reduced, they function just like many other showier flower, and are adapted for wind pollination. The large yellow anthers contain pollen; they hang out of the flower to allow for wind pollination.

The purple spikelets (flowers) of the purple reedgrass (Calamagrostis purpurascens) are just emerging on this plant in Quttinirpaaq National Park, Ellesmere Island, Nunavut.

“Walking around Iqaluit you might get an outsized impression of how abundant grasses are in Arctic ecosystems,” Jeff explains. In the Arctic, grass species are diverse, and have adapted and evolved to fill niches in every type of habitat you can find above the treeline, from shallow waters to tundra expanses and dry, exposed hilltops. But where they really shine is in disturbed areas, where they are often the first group of species on the scene. This means that grass abundance may increase in areas affected by climate change, including where the tundra slumps due to permafrost loss. Under­standing where grass species occur in the Arctic now may prove invaluable as we measure the effects of change in the North.

This love of disturbance also means that Arctic communities are hotspots for grass viewing, and species such as sea lymegrass (Leymus mollis) and Kentucky bluegrass (Poa pratensis) are abundant and readily identifiable in most northern towns. Out on the land in the Arctic Islands, you might find up to 50 different Arctic grass species, assum­ing you have some hiking time on your hands.

Additionally, as our team continues to expand the grass holdings of the National Herbarium of Canada (a national collection of pressed and dried plants), we find more for you to discover, such as species new to science — like the Banks Island alkaligrass (Puccinellia banksiensis) and non-native species popping up in Iqaluit, such as the red fescue (Festuca rubra subsp. rubra).

For both Lynn and Jeff, identifying and sequencing the DNA of Arctic grasses is one part of larger research programs with global scopes. “I love questions of evolution and phylogeny, and you can’t answer [Arctic] questions without looking at the whole picture,” explains Lynn. In collaboration with colleagues in the U.S. and around the world, Lynn continues to work on big evolutionary questions in the bluegrasses (Poa), while Jeff seeks to untangle difficult relationships on brome grasses (Bromus) and reed grasses and their relatives (Calamagrostis).

Perhaps most importantly, grasses are a vital food source to humanity, with nearly half of our global calories coming from domesticated grass species, such as wheat, rice, and corn. Furthering our understanding of Arctic grasses, and perhaps the unique adaptations that let them survive in extreme environments, may be invaluable to a changing world.

Paul C. Sokoloff is Senior Research Assistant at the Canadian Museum of Nature in Ottawa, Ontario.